The invention concerns a filter for filtering in particular liquid fluids, in particular fuel or oil, in particular of an internal combustion engine, as well as for de-oiling air. The filter comprises a filter cup in which a filter element is arranged and a filter head that has at least one inlet for the fluid to be filtered and/or at least one outlet for the filtered fluid. The filter head and the filter cup are connected to each other by means of a releasable or detachable bayonet-type rotation/insertion connection and the rotation/insertion connection has at least two interacting locking parts. One of the locking parts is connected to the filter cup and one of the locking parts is connected to the filter head. At least one of the locking parts has at least one locking nose and one of the locking parts has at least one recess that correlates with the locking nose and is provided with an insertion/removal region that enables resistance-free joining and separating of locking nose and recess and is further provided with a locking region where the locking nose is hooked in bayonet fashion. At least one pretensioning element is provided that acts between the filter head and the filter cup for realizing a pretension of the locking nose in the recess.
The invention concerns moreover a filter cup of a filter for filtering in particular liquid fluids, in particular fuel or oil, in particular of an internal combustion engine. The filter cup is suitable for receiving a filter element and is connectable by means of a releasable or detachable bayonet-type rotation/insertion connection to a filter head. The filter cup comprises at least one locking part of the rotation/insertion connection that has at least a locking nose or a recess that interacts with the locking nose of the filter head and is provided with an insertion/removal region that enables resistance-free joining and separating of locking nose and recess and further provided with a locking region where the locking nose is hooked in bayonet fashion. The filter cup further comprises an engagement section for at least one pretensioning element that is acting between the filter head and the filter cup for realizing a pretension of the locking nose in the recess.
The invention concerns moreover a filter head of a filter for filtering in particular liquid fluids, in particular fuel or oil, in particular of an internal combustion engine. The filter head has at least one inlet for the fluid to be filtered and/or at least one outlet for the filtered fluid. The filter head is suitable to be connected by releasable or detachable bayonet-like rotation/insertion connection to a filter cup in which a filter element can be arranged. The filter head has at least a locking nose or at least a recess interacting with the locking nose of the filter cup and provided with an insertion/removal region that enables resistance-free joining and separating of locking nose and recess and further provided with a locking region where the locking nose is hooked in bayonet fashion. The filter head further comprises an engagement section for at least one pretensioning element that is acting between the filter head and the filter cup for realizing a pretension of the locking nose in the recess.
In air filters that are commercially available, a filter cup in which a filter element is arranged is detachably connected by means of a bayonet connection to a filter head. The filter head has an inlet for the air to be filtered and an outlet for the filtered air. The bayonet connection comprises a locking nose that is connected to the filter head. The filter head has a recess that correlates with the locking nose. The recess comprises an insertion/removal region for resistance-free joining and separating of locking nose and recess and a locking region where the locking nose is hooked in bayonet fashion. Between the filter head and the filter cup a pressure spring is arranged with which a pretension of the locking nose in the recess can be realized. It may happen that, when connecting the filter cup with the filter head, the locking nose is not rotated completely into the locking region. This can cause the filter cup to rotate relative to the filter head in operation so that the locking nose then returns into the insertion/removal region and causes the bayonet connection to release. This leads to operational disturbances and can cause destruction of components of a consumer to which the filtered air from the air filter is to be supplied.
It is therefore the object of the present invention to design a filter, a filter cup and filter head of the aforementioned kind in such a way that the filter cup and the filter head can be reliably and securely connected to each other in a simple way. In particular, faulty assembly should be detectable early on as clearly as possible from the exterior, in particular before, at the latest at the time of, start of operation of the filter.